The present invention relates to a pressure responsive switch or more in particular to a pressure responsive switch having a protection from overpressure of a pressure source, suitable for responding to an intake manifold vacuum and an exhaust gas pressure.
A pressure switch comprising a combination of a diaphragm adapted to be displaced in accordance with pressure and a switch turned on and off in accordance with the displacement of the diaphragm is well known. The pressure switch is used for controlling an internal combustion engine of an automobile by detecting the intake manifold vacuum and exhaust gas pressure of the engine. Such a system is described in U.S. Pat. No. 2,957,463 entitled "Fuel Cut-Off for Carburetor Equipped Engine" and issued to Julius W. Schnabel on Oct. 25, 1960. In the cited system, when a backfire occurs, an excessive shock pressure is applied to the pressure switch, and the diaphragm is likely to be torn or extended to such a degree as to be deformed, thus making the system inoperative or deteriorating the characteristics thereof.